Tonguing \Tongu"ing\, vb. n. (Music)
Modification of tone for a rapid staccato effect by the
performer's tongue, in playing a wind instrument, as a flute.
In {single tonguing} only one kind of stroke is used, the
tongue articulating a rapid "t;" in {double tonguing}, two
strokes, as for "t" and "k," are alternated; in {triple
tonguing}, "t, k, t," etc.
[Webster 1913 Suppl.]